Gunfire erupted again in Ain al-Hilweh camp on Saturday morning and continued throughout the day despite efforts to mediate a ceasefire, a Reuters witness said. Rocket-propelled grenades were also being fired.
Two men were shot dead in the camp on Monday amid tension between members of the mainstream Palestinian faction Fatah and a hardline Islamist group.
Fatah member Hussein Othman was killed in Friday's fighting between groups of armed men, Lebanon's National News Agency said.
Ain al-Hilweh camp, near the southern Lebanese coastal city of Sidon, has regularly seen factional disputes spiral into deadly violence.
The Palestinian camps mainly fall outside the jurisdiction of Lebanese security services.